Glycosilation

Chiral l,2,5-thiadiazolidin-3-one 5,5-dioxides 250 were synthesized by way of conventional methods, with the intention of introducing them in new pseudonucleosides as aglicone (96T(52)993). The synthetic methodology, in accord with previous reports, gave the l,2,5-thiadiazolidin-3-ones in good overall yield (35-55%). The glycosilation was performed on the protected heterocycles to prevent the condensation involving the N-2 atom, the most acidic reactive site. As expected only one anomer was obtained that is the p-one. 

Vitamin K carboxylase is a transmembraneous protein in the lipid bilayer of the endoplasmatic reticulum (ER). It is highly glycosilated and its C-terminal is on the luminal side of the membrane. Besides its function as carboxylase it takes part as an epoxidase in the vitamin K cycle (Fig. 1). For the binding of the y-carboxylase the vitamin K-dependent proteins have highly conserved special recognition sites. Most vitamin K-dependent proteins are carboxy-lated in the liver and in osteoblasts, but also other tissues might be involved, e.g., muscles. 

Four cyanidins with 4 -glucosidation were recently isolated in minor amounts from pigmented scales of red onion. Two were the only anthocyanins with B ring sugar substitutions and no glycosyl moieties in anthocyanidin position 3, whereas the other two were also glycosilated at the usual position 3. ... 

The class II secreted fungal heme peroxidases include the LMPs LiP, MnP and VP [70]. All of these enzymes are extracellular and contain protoporphyrin IX (heme) as prosthetic group. They use H2O2 or organic hydroperoxides as electron accepting cosubstrates during the oxidation of diverse compounds. They are secreted as glycosilated, 35-38 kDa size proteins. 

Isoborneol has been found to be an interesting compound for inhibiting HSV life cycle, on the basis of the specificity of the inhibition of the glycosilation of viral polyptides [137]. Also linalool exhibited the strongest activity against adenoviruses however, carvone, cineole, -caryophyllene, farnesol, fenchone, geraniol, -myrcene and a-thujone did not exhibit activity [135]. 

The insertion of a second oxygen atom in a sugar furanose ring in essence converts that moiety to an acetal. This modiftcation leads to another false substrate for viral reverse transcriptase. Glycosilation of the silylated purine (46-1) with chiral dioxolane (46-2) prepared in several steps from anhydromannose in the presence of ammonium nitrate affords the coupling product as a mixture of anomers (46-3). The mixture of products is then separated on a chromatographic column. The desired diastereomer (46-3) is reacted with ammonia to afford the product (46-4)... 

F. Peri, P. Dumy, and M. Mutter, Chemo- and stereoselective glycosilation of hydroxylamino derivatives A versatile approach to glycoconjugates, Tetrahedron, 54 (1998) 12269-12278. 

Jensen KJ, Meldal M, Bock K, Glycosilation of phenols preparation of 1,2- cis and 1,2- trans glycosylated tyrosine derivatives to be used in solid-phase glycopeptide synthesis, J. Chem. Soc. Perkin. Trans., 1, 2119, 1993. 

J. Stahl-Zeng, V. Lange, R. Ossola, K. Eckhardt, W. Krek, R. Aebersold, and B. Domon, High sensitivity detection of plasma proteins by multiple reaction monitoring of /V-glycosiles, Mol. Cell. Proteomics, 6 (2007) 1809-1817. 

Sc(OTf)3 also catalyzes acetalization reactions [47a,b], acylal formation [47c], /9-selective glycosilation reactions with thioglycosides [48], and acylation reactions of alcohols [49]. Guanidium formation reactions of carbodiimide with benzylamine [50], intermolecular stereoselective radical additions to A/-enoyloxazolidinones [51], and rearrangement of... 

Hakomori, S. (1996). Tumor malignancy defined by aberrant glycosilation and sphingo(glyco)lipid metabolism. Cancer Res. 56, 5309-5318. 

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